Abnormal photoluminescence phenomena in (Tb3+, Eu3+) codoped Ga2O3 phosphor

作者：Sawada Kenji; Nakamura Toshihiro^*; Adachi Sadao^*

来源：Journal of Alloys and Compounds, 2016, 678: 448-455.

DOI：10.1016/j.jallcom.2016.04.004

• Ga2O3
• Phosphor
• Resonant energy transfer
• Degradation
• Lanthanide

The structural and optical properties of (Tb3+, Eu3+)-codoped beta-Ga2O3 crystals were examined using Xray diffraction measurement, photoluminescence (PL) analysis, PL excitation (PLE) spectroscopy, and PL decay measurement. The (Tb3+, Eu3+)-codoped samples were synthesized by metal-organic decomposition (MOD). The PL and PLE measurements showed that the (Tb3+, Eu3+)-codoped samples exhibit clearly different luminescence properties when excited at wavelengths below or above lambda(ex) similar to 350 nm, which corresponds to the boundary in wavelength between the 4f(6) -> charge transfer state and 4f(6) -> 4f(6) transitions to occur in Eu3+. At lambda(ex) > 350 nm, efficient energy transfer occurred from Tb3+ to Eu3+, resulting in the decreased Tb3+ and enhanced Eu3+ emissions. At lambda(ex) < 350 nm, not only the Tb3+ but also the Eu3+ emissions decreased with increasing Tb3+/Eu3+ concentration. Furthermore, the PL intensity degradation in the seconds time scale was observed by exciting light at lambda(ex) < 350 nm. Such unusual PL phenomena at lambda(ex) < 350 nm seem to be due to an interaction between Tb3+ and Eu3+ with producing nonradiative relaxation channels in the Tb3+/Eu3+ emission pathway. The temperature dependence of the PL intensity was also measured at T = 20-450 K in increments of 10 K and analyzed using newly developed models.

• 出版日期2016-9-5